1. Field of the Invention
The present invention relates to a blind with a looped blind sheet for adjusting opacity, especially to a blind with a looped blind sheet including alternate see-through parts and opaque parts. The looped blind sheet is wound between a top rod and a bottom rod to form a front blind sheet and a rear blind sheet. The front and the rear blinds sheets are opposed each other and stretched tightly. The opacity of the blind is adjusted by pulling the front blind sheet or the rear blind sheet.
2. Description of Related Art
Refer to Japanese Patent Publication No. 1995-189573, U.S. Pat. No. 6,189,592, and U.S. Pat. No. 7,267,156, conventional blinds have been disclosed. Blind sheets with alternate transparent and opaque parts with a predetermined width are folded to form a front blind sheet and a rear blind sheet. The blinds revealed in these patents are all roller shades whose blind sheet includes a rolling end. The overlap degree of the transparent and opaque parts between the front blind sheet and the rear blind sheet are adjusted by relative movement of the font blind sheet or the rear blind sheet (only the blind sheet connected with the rolling end moved up or down). And the length of the blind sheet is changed. Moreover, the distance between the front blind sheet and the rear blind sheet should be larger in consideration of the radial thickness of the blind sheet folded around a winding rod, as the winding rod 114 revealed in U.S. Pat. No. 7,267,156. Thus the opacity of the blind is difficult to be adjusted optimally due to this larger distance. Furthermore, the structure of the roller-shade type blind is more complicated than the structure of a blind of the present invention. For example, two ends of the blind sheet are respectively fixed on a winding rod (such as winding rod 114 in U.S. Pat. No. 7,267,156) inside a top supporter, and a fixing rod (such as upper-end support bar 111 in U.S. Pat. No. 7,267,156). And a lifting member (such as adjusting cord/lift mechanism 116 in U.S. Pat. No. 7,267,156) is required to wind up or pull down the blind sheet.
A sliding panel is a kind of a blind. Take a sliding panel 2 shown in FIG. 1 as an example, it includes a rail 201, a plurality of carrier tracks 202 (there is only one carrier track in FIG. 1) arranged under the rail 201, a plurality of panels 203 attached each other and disposed under the carrier track 202, two separate connectors 204 arranged at a top surface of each carrier track 202, and a runner 205 such as a pulley connected to and disposed over each connector 204. By the connector 204 penetrating a channel opening 207 of a channel 206 on bottom of the rail 201, the runner 205 slides inside the channel 206 of the rail 201 so that each carrier track 202 and the corresponding panel 203 slides and extends gradually for shading windows, or folds and overlaps with one another so that the windows are in the see-through state. The panel (no shown in figure, replaced by a blind 1) generally is formed by a blind sheet with preset length (height). Although the blind sheet can be made from various materials, the opacity each panel formed by the blind sheet is constant and unable to be adjusted.
Curtains are also a kind of blind. Take a curtain 3 shown in FIG. 10 as an example. The curtain 3 consists of one rail 301 with at least one blind sheet 302, at least one hook 303 and a curtain rod 304 over a window. The blind sheet 302 is hooked on the curtain rod 304 by the hook 303. The blind sheet 302 (not shown in figure, replaced by a blind 1) is also formed by a piece of fabric with preset length (height). There are various types of fabric with different opacities used to produce the blind sheet 302. Yet the opacity of the blind sheet 302 while already used is still unable to be changed. That means the opacity of the blind sheet 302 is determined. It will keep the same opacity all the time.